Activity_create

Activity Name:

Animal burrows surveys on the Hedwige levee

Activity Numbre:

Activity type

Survey

Involved Workpackage

Flood defences

Emergency response

Knowledge infrastructure

Objective

1. Gain insight into the types of animals that are active in the living lab as well as the geometry and spatial distribution of the burrows they create on the levee. 2. Monitor the levee inspection process and derive lessons that can improve the practices of levee guards. 3. Test feasibility and compare results of two methods for evaluation of burrows; the ground penetrating radar and the smoke method. 4. Identify locations with burrows that could be tested later on, in a large-scale overflow experiment. 5. Compare findings from the application of three different survey techniques and draw lessons for their future use.

Activity Brief descriptor

Data collection on the type, size, spatial distribution of burrows as well as the the underground geometry of burrow systems. This was done with visual inspection, GPR scanning and the so-called smoke test.

Linked to theme(s):

Breaching

Animal- & vegetation-induced anomalies

Erosion processes

Temporary levee repairs

Levee survey & monitoring technique

Prolonged collaboration

Activity Time

Start Date:

Sept. 8, 2021, 8:30 a.m.

End Date:

Sept. 8, 2021, 5:30 p.m.

Active time length:

Days:

None

Hours:

9.0

Other:

Location

Levee stretch:

Coordinates/ Latitude (WGS):

None

Coordinates/ Longitude (WGS):

None

Coordinates/ Altitude (mTAW):

None

Descriptor:

The survey was performed on the inner slope, starting 80.5m SE of the concrete stairs in front the former farm De Cloedt. A levee stretch of 100m was surveyed in total, moving in the direction from NW to SE.

Other references:

Data

Data: 1

Data type: Xls files indicating location and depth of burrows;

Description: Xls files indicating location and depth of burrows;

Date availability: May 31, 2022

Find at: https://stowanl-my.sharepoint.com/:x:/g/personal/llhpp_stowa_nl/EcMu4z7x7k9DhpKWaGfC9roBfQ1FvxNZR93q-S-aLv8VfQ?e=PaNxSP

Media avaliable:

Find media:

Relationships with other activities

Activities that are linked to 48/ Animal burrows surveys on the Hedwige levee :
DB_id: 44/ GPR-Scan DB_id: 57/ 1st Animal burrows survey on the Prosperpolder levee
DB_id: 48/ Animal burrows surveys on the Hedwige levee
DB_id: 48/ Animal burrows surveys on the Hedwige levee linked to the following activities:

No activities

Detaled information about the activity

Pre-conditions

Activity Descriptor

Equipments

Equipment: 1

Probes Fluorescent sprays (4)

Detection of burrows

Equipment: 2

Smartphones with App2C installed

Digital registration of burrows

Equipment: 3

Cameras (2)

Digital registration of burrows

Equipment: 4

Grid paper and pencils

Paper mapping of burrows

Equipment: 5

50m-long measuring tapes (6)

Paper mapping of burrows

Equipment: 6

5m-long measuring tapes (2)

Paper mapping of burrows

Equipment: 7

Leafblower

Smoke test

Equipment: 8

Barrel

Smoke test

Equipment: 9

Smoke bombs (10)

Smoke test

Equipment: 10

Hose

Smoke test

Equipment: 11

Plastic buckets (2)

Smoke test

Equipment: 12

Georadar IDS Opera Duo

GPR scanning

Equipment: 13

Georadar IDS RIS

GPR scanning

Monitoring & Sensors

this activity does not have sensors

Limits

During Activity

- Visual inspection: Burrows made by small rodents were impossible to spot in sections with long grass, while in places where the grass was mowed it was still difficult. The more times that an inspector passed from a spot the more burrows were found. - Burrows registration: App2C was really easy to use, but location data do not provide the level of accuracy that is needed to analyse spatial patterns of burrows. Paper mapping is labour intensive, and could be performed more efficiently than how it was done in this survey. - GPR measurements: The time needed for this activity was underestimated. It took longer than the team had originally expected. On the day the conditions for GPR measurements were very suitable; it was a hot day and it hadn't rained for a while, which made the ground relatively dry. - Smoke test: This test was not successful in this first trial, because a part of the experimental installation was overheated and failed. Still the team managed to detected interconnectedness between 2 burrows.

Post-activity conditions

There was no damage or alteration of the surveyed levee stretch.

Immediate Results

- Only burrows by small rodents were detected (diameters up to 12 cm). - Two spatial patterns of burrows could be discerned in the surveyed area; 1) burrows in a linear setup with orientation in the vertical direction, i.e. crest to toe, and 2) burrows that were clustered close to each other in a relatively small area. - The detected burrows were most likely entrances and exits to underground corridors that lead to dens, which could be situated deeper in the body of the levee. - The largest burrow depth that was registered during mapping was 25 cm, while the GPR results showed that the scanned burrow system reached a depth of 35 cm. In both cases no penetration of the sand core of the levee can be claimed, as the sand core is at 80-100cm depth in this location.

Results /Conclusion

The immediate results are not yet suitable for firm conclusions. They will have to be compared and contrasted with other results of subsequent surveys, and the collected data have to be further processed.

Infrastructure Knowledge

- A set of practical tips for future surveys with a focus on the detection of burrows by small rodents, and guidance for effective use of the smoke test. - Preliminary identification of possible patterns in the spatial distribution of burrows on a levee section.

Other key information